In a well-known system, a high-order apparatus such as a host computer and a low-order apparatus such as a scanner or printer are connected via a network or the like, and image data that has been read in from the scanner is processed and the processed data is printed by the printer.
Improvement in the performance of low-order apparatus such as printers and scanners has been pronounced in recent years. When a new function has been added to such a low-order apparatus, there are cases where a control command is added on anew in order to execute processing using this function. There are occasions where the user of such a system wishes to replace the older low-order apparatus with a low-order apparatus of better performance to which such a new function and control command have been added, and use this low-order apparatus in the same system.
If, e.g., a printer of higher performance is connected and used in such case, the printer driver installed in the high-order apparatus such as a host computer also must be changed in conformity with the printer. In order to accomplish this, usually a printer driver corresponding to the new model of the machine must be re-installed in the high-order apparatus and the printer driver for the new machine must me configured. No problems are encountered if the environment for the re-installation is such that the high-order apparatus has been connected to a public network such as the Internet and, if the new-model printer is found, the printer driver corresponding to this printer is installed automatically. However, in an instance where the high-order apparatus has not been connected to a LAN or network, it is necessary that the printer driver corresponding to this new model be re-installed in the high-order apparatus by the user. This is a troublesome operation for the user.
Further, in a case where it is desired that multiple models of printers be used by a single high-order apparatus, the printer drivers corresponding respective ones of these multiple models are installed and preserved on the, e.g., the hard disk of the high-order apparatus, and the drivers are switched among and used in accordance with the model of the printer to be used. This means that the memory capacity needed to store these drivers must be increased in comparison with the case where a single printer model is connected and used.
In a case where a printer is connected to a host computer, for example, the specification of Japanese Patent Application Laid-Open No. 7-137356 proposes to solve this problem by disclosing a printing system in which a host unit and a printer unit detachably connected. In the disclosed system, a plurality of command tables are stored in the printer RAM beforehand and the command tables of the printer RAM are updated by a command from the host side. This is to deal with a case where there are combinations in which the print commands differ from printer to printer or a case where only the version of the host computer is upgraded. Further, the specification of Japanese Patent Application Laid-Open No. 8-310059 discloses an arrangement in which control data conforming to model-number information of a printer is transmitted to the printer. This is for a case where, when the type and functions of a printer connected to a word processor are known in advance, the optimum control data is transmitted to the connected printer from the printer driver stored in the word processor.
However, the prior art disclosed in the above-mentioned publications cannot cope with a situation in which a new-model printer not anticipated by the host has been connected to the host.
Further, the specification of Japanese Patent Application Laid-Open No. 9-272233 discloses an arrangement in which a high-order apparatus stores the printer drivers of a plurality of printers beforehand and print processing is executed upon selecting a printer driver that conforms to the model of the printer that is to perform the printing. However, this requires that a plurality of printer drivers be stored in the high-order apparatus, as a result of which a very large memory capacity is needed to store the drivers. In addition, as in the case described above, the disclosed arrangement cannot cope with a new-model printer not originally anticipated and a new printer command cannot be added on.
Furthermore, the specification of Japanese Patent Application Laid-Open No. 11-227181 discloses a printer in which printing can be performed upon mounting printheads of different types without changing the printer hardware. In accordance with this arrangement, the controller of the printer on which printheads of different types can be mounted interchangeably transmits data representing the characteristics of the mounted printhead to a host processor, and the controller supplements the print information with profile information concerning the mounted printhead. However, this publication is silent on resolution information concerning the print data, information relating to number of tones, information relating to number of colors used, control-conversion information, print-control command information, print-size information, media-type information, information concerning means for detecting amount of remaining ink, mechanical-mechanism information and operation-assist information, and how these items of information are dealt with is not clear. Further, the host processor in this publication reads information from the printer and stores it as a printer driver in advance in dependence upon this data. The host processor selects a plurality of printhead drive parameters and transmits them to the printer. In this case also, therefore, it is required that the host processor store beforehand parameters corresponding to a printhead to be used. If a new printer is to be added on, it becomes necessary to added on a printer driver that conforms to this printer.
Further, the invention described in the specification of Japanese Patent Application Laid-Open No. 10-226140 relates to an image forming apparatus for forming an image based upon data sent from an external device. This publication proposes that the image forming apparatus store all or a part of a control program of the image forming apparatus that the external device uses. According to this invention, however, the selection of the printer is made in response to an indication from the user, and therefore a malfunction will occur if the user selects the incorrect printer. Further, in the case of an external device that involves difficulty regarding the designation of a selection from the user, as in the manner of a set-top-box information terminal that is one type of home information appliance, selection of a printer will not be possible. In addition, in a case where a control program has been created without limitation, e.g., in a case where the area of a working RAM in an external device has been exceeded, a situation may arise in which control cannot be carried out by the external device. With a printer in which no limitation is placed upon the type of high-order apparatus, there are many cases where limitations on the useable area of a working RAM and other restrictions are imposed depending upon the type of high-order apparatus. If this storage area is exceeded, normal operation cannot be carried out.
Further, in a case where part of a control program is stored in a printer, problems arise in terms of compatibility between this program and a control program that has been stored in the high-order apparatus.
Thus, with conventional systems, it is required that the high-order apparatus on the host side previously store the drivers of low-order apparatus, e.g., printers and scanners, the future use of which is predicted. This means that part of the storage area of the high-order apparatus must always be set aside as a storage area for drivers or the like regardless of whether these low-order apparatus are used or not. Further, in a case where use is made of a printer or scanner of a newly developed model, it is necessary that this driver must be installed in the high-order apparatus.
Further, in the case of a game machine, which is not equipped with a large-capacity rewritable memory device such as a hard disk or flash memory, thereby requiring that the host control program inclusive of a scanner driver or printer driver must be stored in read-only memory means such as a ROM, CD-ROM or DVD-ROM, the conventional high-order apparatus is such that the version of driver corresponding to a low-order apparatus of a new model cannot be upgraded and it is not possible to deal with a low-order apparatus of another model type.